1. Field of the Invention
The present invention relates to an electrical connection box for automotive vehicles and is particularly designed to, when an internal circuitry of the electrical connection box partially differs among different types of vehicles and among different grades of the same type of vehicles, enable the use of the same electrical connection box only by changing a different portion of the internal circuitry.
2. Description of the Prior Art
An electrical connection box used to connect a wiring harness for an automotive vehicle with a variety of wiring devices is adapted to realize a rational and economical junction connection of the wiring by concentrating points of junction connection on one location. A variety of types of such electrical connection boxes are being developed as the wiring harness is made more compact.
Generally, flat busbars formed of a conductive metal plate in conformity with a circuit pattern are used as an internal circuitry of an electrical connection box such as a junction box. A plurality of flat busbars are arranged one over another at a plurality of levels to compact the electrical connection box.
The busbars are formed by suitably bending the punched conductive metal plate. Accordingly, upon a change in the circuit pattern, a mold used to punch the metal plate needs to be changed, and the way the punched metal plate is bent differs. This leads to more labor and an increased cost.
In order to cope with the above problem, Japanese Unexamined Utility Model Publication No. 2-136989 discloses an electrical connection box in which a large current circuitry formed of busbars and a small current circuitry formed of wire and cramping terminals are accommodated at different levels.
Further, Japanese Unexamined Utility Model Publication No. 1-166419 discloses an electrical connection box in which a supply side circuitry connected with fuses F is formed of busbars indicated by bold lines, and a load side circuitry is formed by a combination of a wire and cramping terminals indicated by thin lines in FIG. 10.
The internal circuitry of the electrical connection box differs among different types of vehicles and among different grades of the same type of vehicles.
If the internal circuitry is divided into the large current circuitry and the small current circuitry as disclosed in the above publication No. 2-136989, the construction of the large current circuitry may differ since both necessary and unnecessary circuits thereof differ among different types of vehicles and among different grades of the same type of vehicles. Similarly, the construction of the supply side internal circuitry disclosed in the above publication No. 1-166419 may also differ.
Therefore, even if the internal circuitry is divided into the large current circuitry and the small current circuitry and the large current circuitry is formed by the busbars, or even if the internal circuitry is divided into the supply side circuitry and the load side circuitry and the supply side circuitry is formed by the busbars, the circuit construction differs among the different types and the different grades of vehicles. Therefore, there are many cases where new busbars have to be formed.
On the other hand, even in the small current circuitry formed by the wire and the cramping terminals or even in the load side circuitry, there are small current circuits required for all types and all grades of vehicles at the load side. These circuits include, for example, circuits connected with lamps such as head lights, and a circuit connected with a horn (honker). These circuits are common circuits which are required for any vehicle.
Thus, there is no problem in forming these common circuits by busbars. The formation of these circuits by wire and cramping terminals instead of the busbars may result in more labor to arrange the wire and to mount the cramping terminals.
In view of the above problems, it is an object of the invention to provide an electrical connection box which can be commonly used among different types of vehicles and among different grades of the same type of vehicles by partially changing a circuitry.